do 128 bit numbers work with gradeup & gradedown?
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do 128 bit numbers work with gradeup & gradedown?
Roger Hui, (isnt it always Roger?), had this slick one liner utilizing gradeup that gave the Nth lexical permutation of iota X ...
... but Roger then mentioned something about 64 bit floats only having 53 bits of integer precision.
i'm guessin' that means X is limited to iota 18
does grade up work on the new 128 bit numbers? (and how many bits of integer precision does a 128 bit number have?)
thanks for taking the time & best regards,
TonyC
P.S. this has to do with a wacky idea that i have about speeding up Monte Carlo when using gamma rather than guassian variates
... but Roger then mentioned something about 64 bit floats only having 53 bits of integer precision.
i'm guessin' that means X is limited to iota 18
does grade up work on the new 128 bit numbers? (and how many bits of integer precision does a 128 bit number have?)
thanks for taking the time & best regards,
TonyC
P.S. this has to do with a wacky idea that i have about speeding up Monte Carlo when using gamma rather than guassian variates
- tclviii-dyalog
- Posts: 28
- Joined: Tue Mar 02, 2010 6:04 pm
Re: do 128 bit numbers work with gradeup & gradedown?
Hi Tony
I am informed that 128-bit numbers have 34 decimal digit accuracy - 64-bit floats have 16/17 decimal digit accuracy.
All the primitives that support 64-bit floats support 128-bit decimal values .. just bear in mind that they are significantly slower. And we strongly recommend not switching between ⎕FR←645 and ⎕FR←1287 - there is a rather large "However" section in the ⎕FR documentation - http://help.dyalog.com/17.0/Content/Language/System%20Functions/fr.htm which you should read !
I am informed that 128-bit numbers have 34 decimal digit accuracy - 64-bit floats have 16/17 decimal digit accuracy.
All the primitives that support 64-bit floats support 128-bit decimal values .. just bear in mind that they are significantly slower. And we strongly recommend not switching between ⎕FR←645 and ⎕FR←1287 - there is a rather large "However" section in the ⎕FR documentation - http://help.dyalog.com/17.0/Content/Language/System%20Functions/fr.htm which you should read !
-
AndyS|Dyalog - Posts: 257
- Joined: Tue May 12, 2009 6:06 pm
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